Block Energy Modelling as the Foundation for Success in Transit Fleet Electrification

Block energy modelling is the foundation on which all transit fleet transition planning rests. By comprehending the specific electric power needs for a transit agency’s service blocks, an electrification transition plan can much more accurately assess how far each electric bus in a fleet can travel between charges.

The plan will also determine the number of electric buses an agency will need to adequately serve its public, which will affect other important aspects, such as the required storage yard size and the number of required operators and technicians. Based on when buses are parked in a storage yard between service blocks, block energy modelling can help determine the type of vehicle charging infrastructure required and where it should be located.

A transit agency’s existing diesel-operated service blocks form a natural starting point for an electrification transition plan, as the planning goal is to minimize any transition-related operational disruptions.

However, electric buses have different operating characteristics from diesel buses, with very specific service planning requirements. In particular, battery-electric bus operations are constrained by the range supported by their available battery capacity.

With block energy modelling, the objective is to look at the details of the service blocks currently being used by a transit agency to develop a realistic assessment of how many electric buses will be needed to service existing passenger routes, and to make appropriate service adjustments where needed.

Some of the many factors that come into play in a block energy simulation modelling assessment for electrified buses include:

1. The length and topography of each block
2. The unloaded and loaded weight of the buses
3. Stop frequency
4. Battery power use by ancillary onboard functions such as heating and air conditioning
5. Individual operator skills and habits
6. The lifecycle stage for the batteries powering the buses.

Most transit agencies transitioning from a diesel to an electric bus fleet will do so on a rolling deployment process, with approximately five to 10 per cent of the existing bus fleet replaced each year. With each successive electric bus purchase, it is critically important to maintain a mix of existing and adjusted service blocks that can be supported by a mixed electric-diesel fleet.

Adding to the complexity of transition planning is that electric bus and charging technology continues to evolve over time to accommodate larger battery capacities and higher charging rates. In response, transition plans, including service block adjustments and charging infrastructure changes, should be updated every few years as the technology changes.

Block energy modelling assessments need to be periodically adjusted based on the most accurate and current data available, so that the intelligence they generate on the steps needed to support every stage of the fleet transition can be most effective.

Using an intelligence-based modelling approach to plan all aspects of a fleet electrification transition is the best way to ensure that every investment a transit agency makes in electric vehicles and supporting charging infrastructure will ultimately contribute to the overall transition while avoiding poorly utilized assets or wasted costs.

In my next IBI Insights article on bus fleet electrification, I will look at what the future may hold for transit fleet electrification. The goal is to help agencies plan for the transition to a more environmentally sustainable public transit model with well-understood capital and operating costs.